Electrical instrument for determining top dead center position in internal-combustion engines



June 13, 1950 G. J. WOREL. 2,511,392

ELECTRICAL INSTRUMENT FOR DETERMINING TOP DEAD CENTER POSITION IN INTERNAL-COMBUSTION ENGINES Filed July 21, 1948 IN VENTOR. GLEN J'. WOREL A TTORNEYS Patented June 13, 1950 ELECTRICAL INSTRUMENT FOR DETERMIN- ING TOP DEAD CENTER POSITION IN IN- TERNALCOMBUSTION ENGINES Glen J. Worel, Minneapolis, Minn., assignor to Thexton Manufacturing Company, Minneapolis, Minn., a corporation of Minnesota Application July 21, 1948, Serial No. 39,946

7 Claims. (01. 177-311) This invention relates to'an electrical instrument for determining and indicating top dead center position of one of the pistons of an internal combustion engine to enable a mechanic to readily make proper adjustment in the settings of the distributor and related vacuum control mechanism which determine the advancing or retardation of the spark in the related cylinder.

Internal combustion engines, particularly of the modern automotive type have distributors which successively control the firing circuits to the several spark plugs of the engine and which must be set or adjusted to cause firing to take place at the proper time in the several cylinders, taking into consideration the various speeds of the motor as well as the variance in partial vacum created in the intake manifold. Most automotive motors have distributors provided for adjustment of the breaker points and have also a distributor vacuum adjustment which correlates adjustment of the distributor in proper response to variance in partial vacuum produced in the intake manifold.

With several conventional types of automotive engines, it is diflicult without removing the motor head, to determine the top dead center position of a cylinder. With some automotive engines, the spark plug socket is sufficiently large to receive a mechanical gauge or indicator which may be associated with the piston of one of the cylinders, usually the number one cylinder of the right hand bank. In the various models of Ford automobile, the motors and spark plug sockets are so constructed that the motor head must be removed to ascertain top dead center position and furthermore, in Ford motors; no marking or dial plate is provided by the manufacturer.

It is an object of my present invention to provide an electrically operated instrument to detect and indicate by signal when a selected piston of an internal combustion engine is positioned at top dead center.

A further object is the provision of a signaling top dead center indicator which may be readily and preferably visually cooperated with a timing plate and pointer to enable a mechanic to readily check the firing of a predetermined cylinder and consequently, the timing of the other cylinders of the motor during slow and high speed and to thereby, with accuracy, make the necessary adjustments of the distributor breaker points and the distributor vacuum adjustment.

More specifically, it is an object to provide a piston-actuated-rod which may be in erted 2 through the spark plug socket and aperture of any cylinder in conventional types of automotive and other internal combustion engines, mounted to be slidably adjusted upwardly by movement of the piston in approaching and reaching top dead center position and so set and provided with a light or other visible or audible signal at its up er end and with an electrical con tact and conductor system to cause a signal. to be given each time the piston returns to top dead center position.

Another object is the provision of an instrument of the class described which very accu, rately positions a rod to indicate top dead center position of a selected piston of an engine with means for retaining the rod in its adjusted po@ sition of such a nature as to offer no impediment to sliding of the rod in the actuation thereof.

These and other objects and advantages of my invention will more fully appear from the follow-, ing description made in connection with the ac: companying drawings wherein like reference characters refer to the same or similar parts throughout the several views and in which:

Fig. l is a perspective view of a conventional ype of engine having an embodiment of my in: vention applied thereto and having also mounted thereon, a timing plate and pointer;

Fig. 2 is a view mostly in side elevation with portions broken away and others shown in section of my instrument, detached;

Fig. 3 is a perspective view of a form of timing plate adapted to fit certain models of a Ford motor; and,

Fig. 4 is a view partly in side elevation and, partly in vertical section of an adapter for use with the sleeve mounting of my device.

In Fig. l, a Ford automotive engine .is illustrated with a portion of the top of one bank Oi. cylinders sectioned vertically to illustrate the mounting and operation of an embodiment of my invention applied thereto. The internal combustion engine has the number 1 piston P of the right hand bank shown in its uppermost or top dead center position in the block MB. The motor is provided in its top with the usual tapped sockets for receiving the spark plugs, one of which, S, (for the number 1 right hand bank of. cylinders) receives and supports my improved instrument. The engine'is further provided with the usual .fan belt driving pulleyFD fixed to the pulley shaft .X, and having a retaining nut N secured to the threaded end of the shaft in eon-..

ventional manner.

or support, a metal or plastic sleeve 6 having an externally threaded lower end So adapted to threadedly engage the spark plug receiving socket S of a conventional type of automotive motor such as the Ford. Sleeve 6 has a smooth cylindrical passage formed axially thereof slidably receiving the intermediate portion of a tubular piston engaging rod 1. Rod I has its lower end bent at right angles to the body thereof to form an arm Ia, the outer extremity of which is closed by a di-electric plug 8 having mounted therein, a depending, hardened metal contact point 9 adapted to be abutted by the upper surface of the head of the piston of the internal combustion engine.

I provide simple but highly efficient rod-retaining means in mounting sleeve 6 adapted to permit rod I to be freely elevated in sleeve 6 by upward movement of piston P while, nevertheless, frictionally retaining the rod 1 and the electric signal carried thereby in the various adjusted positions of the rod relative to mounting sleeve 6. This retaining mechanism, as illustrated, comprises a small spring pressed metal ball I seated in an aperture formed in a circumferential groove 6b which is machined in the metal circumferential portion of sleeve 6. The seat for ball I0 conforms to the spherical shape of the ball and is of such diameter that the ball is pressed lightly against the periphery of the rod 7. A split annular spring member I I is seated in the groove Eb externally of ball I0 and urges the ball inwardly against the rod.

At the upper end of rod 1, a signal mounting is afiixed preferably in the form of a sleeve I2 constructed of di-electric material. As shown, sleeve I2 has its lower end affixed to a diminished shoulder of a solid base element I3 which is axially apertured at its lower end to receive and be rigidly afiixed to the upper end of rod 1. A set screw I4 as shown, clamps the signal housing or mounting to the rod.

The di-electric sleeve I2 has mounted within the upper portion thereof, a small metal electrical socket I5 for receiving the stem I 6a of a small electric lamp I6. Socket I5 has mounted within the lower portion thereof, a di-electric plug I 1 in which is axially fixed, a conductive contact stud IIa, the upper end of which projects slightly above the upper end of plug I! for abutting the conductive terminal at the end of the lamp stem.

An insulated electric conductor I8 extends upwardly through the tubular rod 1 connected electrically at its lower end with the depending contact 9 and extending into the sleeve housing I2 and having its upper extremity electrically connected with the metal socket sleeve I5. An electrical clamping post I9 is affixed externally to the medial portion of di-electric housing I2 and has its inner end within the housing electrically connected by an insulated conductor I9a with the lower end of the conductor stud I M for supplying the lamp. Clamping post I9 is adapted to be electrically connected by an insulated conductor 20 with the negative post of a battery as indicated in Fig. 1.

To facilitate mounting and insulation of my apparatus in internal combustion engines of different types, I provide suitable adapters such as shown in Fig. 4 comprising a collar 2|, internally threaded at 2Ia to receive the threaded lower end 6a of my sleeve mounting and externally threaded at 2I'b to threadedly fit the particular spark plug socket for which the adapter is intended.

With my electrical instrument and closely cooperating therewith, when testing of distributor setting is made to determine needed adjustment, I prefer to supply a timing plate 22 adapted to be adjustably fixed to the shaft of the fan driving pulley FD and a pointer plate 23 adapted to cooperate with the segmental scale 22a of the timer plate 22. As shown in Fig. 1, the timing plate 22 comprises a flat plate having a circular attachment portion 22b concentrically apertured to closely flt the shaft X of the fan pulley. Plate 22 has a segmental outturned flange at its outer end adapted to be disposed at the periphery of the fan pulley and having applied thereto the graduated dial 22a. preferably marked with two readings T. D. C. and I G N. The graduations preferably correspond to the degrees in a circle of revolution. The top dead center position of a piston due to the connecting rod driving means, stays constant for approximately four degrees. The T. D. C. reading is thus positional centrally of such four degrees. The I G N" reading is indicated on the dial for an engine of the Ford Motor Company, which normally has its firing point at slow speed disposed four degrees ahead of top dead center position. Cooperating with the timing plate 22, I provide a pointer plate'23 of general arcuate shape conforming to the marginal portion of the removable end of the cylinder block of the engine and having at one end, an aperture for accommodating the bolt A for securing said end to the block and having at its opposite extremity a slot for engaging and accommodating the bolt B as shown in Fig. i. A pointer arm 23a is extended at right angles to plate 23 terminating in a point which overlies the graduated dial 22a of the timing plate.

In Fig. 3, I illustrate an alternate form of timing plate 25 which has a flat apertured body with an upper out-turned segment flange provided with a graduated dial plate 25a fixed thereto. The lower end of the body of plate 25 is integrally formed with a half-collar clamping element 25b having out-turned flanges which cooperate with the out-turned flanges 26a of a half-annular clamping element 26. The collar formed by elements 25b and 26 is adapted to be clamped upon the pulley hub in certain models of internal combustion engines such as the 1938 to 1948 models manufactured by Ford Motor Company.

I I prefer to provide in the connected lower end of the sleeve moimting 6, air ports to permit escape of air during the upward movement of piston P. To this end, one or more longitudinally disposed grooves '60 are formed externally in the lower extremity threaded portion 6a of the mounting sleeve. Said grooves extending from the lower extremity upwardly through the flange at the top of the threaded portion.

Operation The rod 1 is then moved downwardly in the friction sleeve mounting 6, so that it will be elevated by the upward movement of the piston. It is usually advisable to depress and oscillate the rod I by manipulation of the housing I2 to scrape carbon from the top of the piston and thus pro-- 8 duce-metal to metal contactbetweenthepiston head P and the metal contact 9 on the'out-tur'ned arm Ia of the rod. The operative position of the indicator rod 1 for contact between point 9 and the piston P is determined from the position of the indicator housing by the fact that the terminal I9 is disposed oppositely on the axis ofrod Ito the positioning of the arm la.

The crank shaft is slowly turned to elevate piston P and with it, of course, the indicator rod I until the signal is given by completion of an electrical circuit throughthe lamp or other signaling device 16. The timing plate 22 is then oscillated on the shaft of the fan belt driving pulley to a position where pointer arm-23a is two degrees past the T. D. C. marking on the graduated dial of plate 22.

The crank shaft may then befurther turned and the lamp will be illuminated at a position two degrees before the reading T. D. C. is reached on the dial 22a and will sta illuminated until a reading two degrees past the T. D. C. reading is reached showing that the timing plate is installed correctly.

In the functioning of my instrument, the friction retaining means offers no impediment to upward sliding movement of the rod 1 within sleeve 6, but nevertheless, retains the rod in the uppermost adjusted position.

The rod 1 carrying the out-turned arm 1a is of such small diameter that it may be readily slipped through the apertured socket of the spark plug and the rod turned in so doing to dispose arm la parallel with the top of piston P. Thus, my improved instrument may be readily installed on all conventional types of automotive engines and on most commercial internal combustion engines without removing the top from the engine block.

The close cooperation between the slidable rod 1 and its tubular mounting 6 with the spring pressed friction ball I provides a highly accurate signalling device for indicating the precise top dead center position of a piston.

Since it is known that a piston of an internal combustion engine remains at top dead center position for four degrees of its revolution, the timing plate may be correctly set at two degrees past top dead center position when the light is illuminated in the operation of my device.

With the timing plate provided, set for top dead center position, my instrument ma be removed and the spark plug installed with standard timing light connection for adjusting the settings of the several adjustments on the distributor.

From the foregoing description, it will be seen that I have provided a simple, highly accurate and economical instrument for quickly and easily determining and indicating the top dead center position of a piston. It will further be seen that with my structure, automotive engines such as those manufactured by Ford Motor Company utilizing unusually small spark plug sockets, may be readily tested and top dead center position determined and. thereafter my timing plate and pointer attached to the motor to give the accurate reading.

It will, of course, be understood, that various changes may be made in the form, details, arrangement and proportions of the parts without departing from the scope of my invention.

What I claim is:

1. An electrical instrument for determining top dead center position of a piston-type engine,

comprising" an upstanding mounting adaptedto be secured to the top of an engine, adjacent one of the pistons, a rod: sl-idably accommodated in said mounting for movement by actuation of the piston in a path substantially normal to the, top of said piston, said rod having a depending electrical contact at the lower portion thereof, disposed in the path of the head of said piston, an electrical v signal device disposed above said mounting and having one of its terminals electrically connected with said contact, means for connection of the other terminal of said signal with a' source of electromotive forces grounded to said piston and means for retaining said rod in the topmost position to which it is raised by the upward movement of said piston.

' '2. The structure set forth in claim 1. and said rod having a lower end angled with reference to the body thereof and being of a diameter to enable insertion of said rod through an open spark plug socket of an engine with said arm ultimately extending parallel to the top of a piston and with said contact disposed in the path of said piston.

3. An electrical instrument for determining top dead center position of a piston type engine, comprising an upstanding mounting adapted to be secured in a spark plug socket of an engine adjacent the corresponding piston, a rod slidably accommodated in said mounting for longitudinal movement by actuation of the piston substantially normal to the top of said piston, said rod having at its lower end, a depending electrical contact disposed in the path of the top of said piston and offset from the body of said rod, an electrical signal device secured to the upper portion of said rod above said mounting and having one of its terminals electrically connected with said contact, means for connection of the other terminal of said signal with a source of electromotive forces grounded to said piston and means for retaining said rod in the topmost position to which it is raised by said piston.

4. The structure set forth in claim 3 and said last mentioned retaining means comprising a spring pressed clement carried by said mounting and frictionally engageable with said rod.

5. An electrical instrument for determining top dead center position of a piston type engine, comprising an upstanding mounting adapted to be secured in a spark plug socket of an engine adjacent the corresponding piston, a rod slidably accommodated in said mounting for longitudinal movement by actuation of the piston substantially normal to the top of said piston, said rod being tubular and having its lower end angled at substantially degrees to the body thereof and carrying a depending, insulated electrical contact disposed in the path of the top of said piston and offset from the body of said rod, an electrical signal device secured to the upper portion of said rod above said mounting, an insulated conductor extending through said rod connected at its lower end to said contact and at its upper end with one of the terminals or said signal device, an electrical terminal secured in insulated relation to said signal device and electrically connected with the other terminal of said signal and being disposed diametrically oppositely from the positioning of the angled end of said rod to enable positioning of said angled end relative to said piston to be determined from above the engine and means interposed between said rod and said upstanding mounting for retaining said rod in the topmost position to which it is raised by said piston.

6. The structure set forth in claim 5 wherein said signal device comprises a housing having mounted therein, an electric lamp socket and an electric lamp detachably secured in said socket, the lower end of said housing being secured to the upper end of said rod.

'7. An electrical instrument for determining top dead center position of a piston-type engine, comprising an upstanding mounting adapted to be secured to the top of an engine, adjacent one of the pistons, a rod slidably accommodated in said mounting for movement by actuation of the piston in a path substantially normal to the top of said piston, said rod having a depending electrical contact at the lower portion thereof, disposed in the path of the head of said piston, an electrical signal device disposed above said mounting and having one of its terminals electrically connected with said contact, means for connection of the other terminal of said signal with a source of electromotive forces grounded to said piston, said upstanding mounting having a crcular aperture therein, communicating with the periphery of said rod and forming a ball-receiving seat, a ball disposed in said seat and engaging said rod and a spring for urging said ball against the periphery of said rod to retain said rod in an adjusted position within said mounting.

GLEN J. WOREL.

I REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,149,620 Museus Mar. 7, 1939 20 2,361,462 Dickinson Oct. 31, 1944 

